Going by this anthropological definition, Mumbai's railway tracks are already running the gauntlet of the Stone Age. Only the roles are slightly reversed. The baddie isn't given the third degree by the good guys. Here trains packed with 58 lakh commuters, many of them crowding near doorways, run between rows of roving miscreants armed with stones.

In an all-time high 40 stones have found their mark on the city's commuters this year, depriving some of vision and scarring the wits of others. What was earlier a Holi phenomenon has now become a year-round event. Stones have replaced water balloons, adding new chapter to the commuter's book of hazards.

For every vicious missile attack, two or three go unreported. A female commuter standing on the footboard next to a colleague was bumped on the head by a flying missile. The pain only strengthened her resolve to get home faster.

Travel in a local train to hearthe clunk of a stone bouncing off the train's exterior and watch the uneasy commuters retreat within the train.The footboard that offered the only gasp of fresh air in trains loaded to crush dense capacity, is now akin to walking the legendary plank on pirate ships. There are no sharks here, just the prospect of a cracked skull, a steep fall from a speeding train, or both.

Searching for solutions in this peculiar problem mired in socio-economics is as frustrating as the efforts of the Government Railway Police (GRP) to curb the menace.

`All stones are thrown by hutment dwellers mainly at the women's compartments.' Right? Wrong. The police say there's no pattern to these incidents. At least half of the stones have whizzed in from roads adjoining railway tracks, bridges, from deserted stretches of railway track and even from other trains. Men, women and children, everyone's fair game in this macabre sport.

Periodic videographing of the hutments from local trains was tried out in an attempt to ward off atleast half of the potential stone pitchers. It failed after the costs failed to produce results.

Then came a rash of incidents this year beginning with one where a commuter lost her eye and GRP personnel were rushed onto the railway tracks.But a pair of constables stumbling along a four-kilometre track for a whole day, dodging trains and side-stepping excreta, wasn't exactly proving effective.

Mumbai's suburban railway system which runs over 480 kilometres is amongst the densest in the world. Policing it's entire stretch proved to be an impossibility as the GRP discovered.

The incidents continued unabated, so in a mohalla committee approach, the GRP appealed to hutment dwellers to watch the tracks themselves. This too has met with limited success.

And as these harried policemen will tell you, the fault doesn't lie entirely with the slum dwellers. Commuters on passing trains sometimes hurl the worst of taunts at hutment dwellers answering nature's call. The womenfolk come in for special attention,prompting retaliation.

Tourists have been left astonished by Mumbai's trains which are probably the only ones in the world which run without automatically shutting doors. But then trains abroad are well ventilated and don't carry a tenth of Mumbai's passenger load.

The short-term solution to ensure commuter safety, is to rush with the installation of automatically shutting doors and installing wire meshes on windows.

This experiment was tried out a few years back, when imported doors were installed on local trains. However, these doors just wouldn't shut because of the heavy passenger loads. Well, the stones weren't flying in as hard and fast then, so well ventilated metal doors are an option that must be quickly explored.

Rehabilitating the slum dwellers as quickly as possible would take off a bulk of stone throwing cases. A zillion schemes to resettle hutments have already been floated but have remained firmly paperbound. Permanent solutions are always the toughest.

Foreign consultants hired bythe railways have prepared some radical train re-engineering designs to be financed by the World Bank under the Mumbai Urban Transportation Project (MUTP-II). But these sleek, sealed and well ventilated trains won't come in until 2005. So until then, Mumbai's resilient commuter who has battled everything from waist high water and body odour to catch trains, will have to forgo two of his indulgences: travelling on the breezy footboards and grabbing the prized window seats.